widgets: Checkbox: Add a simple checkbox widget

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>

wasp/apps/testapp.py

@@ -25,10 +25,12 @@ class TestApp():
     ICON = icons.app
 
     def __init__(self):
-        self.tests = ('Alarm', 'Button', 'Crash', 'Colours', 'Fill', 'Fill-H', 'Fill-V', 'Free Mem', 'Line', 'Notifications', 'RLE', 'String', 'Touch', 'Wrap')
+        self.tests = ('Alarm', 'Button', 'Checkbox', 'Crash', 'Colours', 'Fill', 'Fill-H', 'Fill-V', 'Free Mem', 'Line', 'Notifications', 'RLE', 'String', 'Touch', 'Wrap')
         self.test = self.tests[0]
         self.scroll = wasp.widgets.ScrollIndicator()
 
+        self._checkbox = wasp.widgets.Checkbox(4, 104, 'Check me')
+
         self._sliders = (
                 wasp.widgets.Slider(32, 10, 90, 0xf800),
                 wasp.widgets.Slider(64, 10, 140, 0x27e4),
@@ -72,7 +74,9 @@ class TestApp():
         self._draw()
 
     def touch(self, event):
-        if self.test == 'Colours':
+        if self.test == 'Checkbox':
+            self._checkbox.touch(event)
+        elif self.test == 'Colours':
             if event[2] > 90:
                 s = self._sliders[(event[2] - 90) // 50]
                 s.touch(event)
@@ -221,7 +225,9 @@ class TestApp():
         if self.test == 'Alarm':
             draw.string("Press button to", 12, 24+24)
             draw.string("set alarm.", 12, 24+48)
-        if self.test == 'Crash':
+        elif self.test == 'Checkbox':
+            self._checkbox.draw()
+        elif self.test == 'Crash':
             draw.string("Press button to", 12, 24+24)
             draw.string("throw exception.", 12, 24+48)
         elif self.test == 'Colours':

wasp/icons.py

@@ -332,3 +332,16 @@ no_button = (
     b'?\x1c\xc1\x03\xc1?\x1c\xc1\x03\xc1?\x1c\xc1\x03\xc1?'
     b'\x1c\xc1\x03\xff\x1e?\x83'
 )
+
+# 2-bit RLE, generated from res/checkbox.png, 108 bytes
+checkbox = (
+    b'\x02'
+    b'  '
+    b'\x02\xdc\x03\xde\x01\xe4X\xc7Z\xc6Z\xc6Z\xc6T\x82'
+    b'D\xc6S\x84C\xc6R\x86B\xc6Q\x86C\xc6P\x86'
+    b'D\xc6O\x86E\xc6N\x86F\xc6M\x86G\xc6L\x86'
+    b'H\xc6D\x82E\x86I\xc6C\x84C\x86J\xc6B\x86'
+    b'A\x86K\xc6C\x8bL\xc6D\x89M\xc6E\x87N\xc6'
+    b'F\x85O\xc6G\x83P\xc6H\x81Q\xc6Z\xc6Z\xc6'
+    b'Z\xc7X\xe4\x01\xde\x03\xdc\x02'
+)

wasp/widgets.py

@@ -215,6 +215,47 @@ class ScrollIndicator:
         if self.down:
             draw.blit(icons.down_arrow, self._pos[0], self._pos[1]+13, fg=color)
 
+class Checkbox():
+    """A simple (labelled) checkbox."""
+    def __init__(self, x, y, label=None):
+        self._im = (x, y, label)
+        self.state = False
+
+    def draw(self):
+        """Draw the checkbox and label."""
+        draw = wasp.watch.drawable
+        im = self._im
+        if im[2]:
+            draw.string(im[2], im[0], im[1]+6)
+        self.update()
+
+    def update(self):
+        """Draw the checkbox."""
+        draw = wasp.watch.drawable
+        im = self._im
+        if self.state:
+            c1 = wasp.system.theme('slider-default')
+            c2 = draw.lighten(c1, 15)
+            fg = c2
+        else:
+            c1 = 0
+            c2 = 0
+            fg = wasp.system.theme('accent-lo')
+        # Draw checkbox on the right margin if there is a label, otherwise
+        # draw at the natural location
+        x = 239 - 32 - 4 if im[2] else im[0]
+        draw.blit(icons.checkbox, x, im[1], fg, c1, c2)
+
+    def touch(self, event):
+        """Handle touch events."""
+        y = event[2] + 4
+        im = self._im
+        if y >= im[1] and y < im[1]+40:
+            self.state = not self.state
+            self.update()
+            return True
+        return False
+
 _SLIDER_KNOB_DIAMETER = const(40)
 _SLIDER_KNOB_RADIUS = const(_SLIDER_KNOB_DIAMETER // 2)
 _SLIDER_WIDTH = const(220)